The long-term goal of the proposed research is to identify genetic and behavioral factors which influence cancer risk and prevention efforts of individuals with inherited predisposition for colorectal cancer (CRC). Clinical genetic testing has become increasingly available for patients with familial CRC;however at present there are insufficient data to assess its impact on clinical outcomes. Although endoscopic screening reduces morbidity and mortality from CRC, preliminary data suggest that many individuals at highest risk do not undergo screening that is adequate for cancer prevention. This research will examine whether interventions, such as genetic testing and cancer risk assessment, improve cancer surveillance and clinical outcomes. We will also explore associations between clinical phenotypes and genotypes in order to define cancer risks and guide prevention efforts for patients with hereditary cancer syndromes. The research projects and educational curriculum in this proposal complement the candidate's training in gastroenterology and public health, providing additional experience in research methods and genetic epidemiology to advance her career to become an independent clinical investigator. Three studies are described in this proposal. A cross-sectional questionnaire study of 400 individuals with Hereditary Nonpolyposis Colorectal Cancer (HNPCC) will provide baseline data on cancer prevention behaviors and will identify clinical characteristics associated with appropriate cancer surveillance in individuals at high risk for CRC. A longitudinal study of individuals undergoing genetic testing for familial cancer syndromes will examine short term and long-term impact of clinical genetic testing on medical decision-making and cancer screening. Examination of genotype-phenotype correlations in a large cohort of individuals who have undergone clinical genetic testing will allow study of variations in cancer risk observed in familial CRC. These studies encompass cancer prevention, behavioral and epidemiologic research. Although we target a population of individuals at risk for familial CRC syndromes, this research has direct relevance for cancer prevention in other groups. Identification of factors which impact cancer screening behaviors and cancer risk stratification will lead to improvements in clinical care for all patients at risk for CRC.